The memo was written by Senate GOP lawyer Michael Carvin and argued that the methodology used uring the 2002 reapportionment, when applied to he current population, calls for the addition of a new seat.

“I continue to believe that this methodology is the most faithful to the Constitution,” Carvin wrote. “I note that if the 2002 methodology is again employed, the size of the New York State Senate will be increased to 63 senators.”

Reif said no decisions have been made about the location of a new district. Final maps for new Senate districts will be available by the end of the month, he added.

Democrats and good government groups have slammed the Republicans, saying there’s no legal justification for adding a new seat and the move was likely fueled by politics.

“As the calculations have been done for us, any way we look at it, it comes to 62,” said Susan Lerner of Common Cause, N.Y. “They don’t get to just decide to have 63.”

The Senate’s move is all-but certain to spark a court battle and could draw fire from Gov. Cuomo, who in his State of the State address Wednesday promised to veto any lines not created through “an independent redistricting process.”

Insiders note that adding a 63rd seat in the state Senate could make it easier for the GOP to retain their razor-thin majority in the upcoming elections and avoid any legislative chaos by ensuring one party would be in the majority – as opposed to now, with an even number of seats.

State lawmakers are redrawing their districts – and congressional districts – as part of a census-mandated rejiggering.